First, you need to go to a taqueria. As Peter explained, you just need to add -ria to the end of most nouns to get "a place who makes _____". And thus, a taqueria specializes in just that, tacos. At a very good taqueria, you can really only get a few things, tacos, maybe a torta, and a soda or beer. That's it. Taquerias are generally dive-y places, not known for high levels of apparent cleanliness, amenities, or bathrooms (particularly bathrooms). But, you can always tell a good taqueria, it will look like this one in Cuernavaca
Good tacos come from simple ingredients. Many gringos are confused when they first try a GOOD taco because it looks so naked. Just a little sliced al pastor (or tongue or carne asada or chicken or something), cilantro, and onion all served on tiny 3-4 inch corn tortillas with lime and green and red salsas on the side. At a fancy place you might have pico de gallo as well. That's it. No lettuce. No cheese. No sour cream for heaven's sake. Simple and delicious. And you certainly can't eat just one. In fact, I've been known to eat 6 on my very own. MMMMmmmmmm
The best GOOD tacos to get are tacos al pastor. Al pastor is a mysterious meat rotisserie that looks a lot like the gyro or kebab places in Europe. The meat sits all day, slowly spinning as the guy in charge skillfully slices small amounts for you.
And the best place to get them is in Mexico City... down the street from our hotel and next to the chicken rotisserie (mmm another post about that sometime!). At that taco place, we waited for a table to clear (from the 5 available ones), and parked ourselves down and ordered, what else, but tacos. They came, delightfully warm and juicy, right off the spinning al pastor machine, topped with tiny bits of pineapple with the cilantro and onion. At the best places, a whole fresh peeled pineapple is placed at the top of the rotisserie and the juices drip down over the meat, adding to the flavor. And at any place, these tacos are CHEAP! Generally, we found tacos to be between 4-8 pesos a taco (10 pesos=1 dollar). And with a llimited menu, you certainly aren't tempted to upgrade or go "high-end".
I'm missing the al pastor a lot by now. I have a good carnitas recipe, but it's just not the same. When you go to Mexico, you must eat a real taco, it will change your world.

